Soft contact roll for a single facer

ABSTRACT

A soft contact roll is mounted immediately downstream of the generator roll in a single facer to press the freshly glued single face web against the surface of the heated fluted bonding roll with a light load uniformly distributed across the full width of the web. The contact roll helps spread the adhesive more quickly and uniformly.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a single facer for theproduction of a single face corrugated paperboard web and, moreparticularly, to an auxiliary soft contact roll mounted immediatelydownstream of the line of joining the liner web with the gluedcorrugated medium web on the corrugated bonding roll to enhance thequality of the glue bond.

[0002] Recent development in single facers for the production of singleface corrugated web include the elimination of a high load pressure rollfor providing an initial adhesive bond and instead using a largediameter heated corrugating roll on which the single face web isretained after joinder of the component webs to provide an initial greenbond in the glue lines before the single face web leaves the bondingroll. It was discovered that the relatively high impact pressure roll ina prior single facer provided an initial mechanical bond, but tended tosqueeze the starch adhesive from the flute tips so that a less thansatisfactory final bond resulted. Furthermore, the freshly formed singleface web was removed from the corrugating roll before an adequate greenbond was formed and also subjected to flexing movement which coulddisrupt the glue lines before an adequate bond was formed.

[0003] In an improved single facer construction, the freshly gluedsingle face web was retained on and wrapped around a significant portionof a large diameter fluted and heated bonding roll, on which the mediumweb was also corrugated, so that an adequate green bond could be formedin the glue lines before the single face web was removed from thebonding roll. An apparatus of this type is shown, for example, in U.S.Pat. No. 6,149,751, the disclosure of which is incorporated by referenceherein. In such an improved single facer, web tension alone was found toprovide adequate force to hold the component webs together on thebonding roll while adhesive green bonds formed.

[0004] In some cases, however, it was found that the web tension bywhich the freshly glued single face web was wrapped on the flutedbonding roll did not provide a sufficient force to adequately hold theliner web in contact with the glued flute tips of the corrugated mediumweb and to spread the glue for an optimum bond. It has been found to beimportant to press and spread the freshly applied glue lines between themedium flute tips and the liner before gelatinization of the starchadhesive to assure uniform and optimum penetration of adhesive into thefibers of both webs. Once the adhesive has gelled, it becomes moredifficult to spread and does not penetrate the paper as well. Thepresent invention, therefore, provides an apparatus and method forenhancing the bond in a freshly glued single face web by providing anauxiliary pressure radially against the single face web on the bondingroll.

SUMMARY OF THE INVENTION

[0005] In accordance with the present invention, an auxiliary contactroll is mounted downstream of the line of initial tangent contactbetween the liner web and the glued corrugated medium web to press thesingle face web against the bonding roll with a relatively light radialforce distributed uniformly across the width of the single face web. Thecontact roll is mounted with its axis of rotation parallel to therotational axis of the bonding roll and is mounted directly adjacent themeans by which the liner web is brought into contact with the gluedcorrugated medium web, typically a generator roll around which the lineris delivered and brought into tangent contact with the medium web. Theouter surface of the contact roll is provided with a relatively softrubber cover or coating to protect the bonding roll from damagingcontact when no web is present and to accommodate slight misalignmentsduring operation.

[0006] The contact roll includes a roll end support mechanism that isoperative to vary the position of the contact roll radially with respectto the bonding roll and to vary the loading of the contact roll againstthe single face web. In the preferred embodiment, the contact rollcomprises a center dead shaft including stub shaft ends connected to theend support mechanism, and an outer shell that is rotatably supported onthe dead shaft by a plurality of axially spaced bearings.

[0007] The support mechanism for the contact roll comprises an eccentriccoupling fixed at one end to each of the stub shaft ends, each couplingproviding a connection to a pivot shaft at its other end, each pivotshaft in turn journaled for limited rotation on a pivot axis parallel tothe axis of the dead shaft, and an actuator connected to each pivotshaft and operative to provide the limited rotation of the pivot shaftto vary the position of the contact roll with respect to the bondingroll and the single face web wrapped thereon. In the preferredembodiment, the actuators comprise pneumatic cylinders, each having acylinder rod end connected eccentrically to one of the pivot shafts.

[0008] The contact roll dead shaft preferably includes a larger diameteraxial center portion that joins reduced diameter opposite end portions,and the outer shell has an axial center portion with a larger wallthickness joining opposite shell end portions of reduced wall thickness.Preferably, the axial center portions of the dead shaft and the outershell are approximately equal in length. The outer shell is preferablyrotatably supported by a pair of bearings positioned adjacent the endsof the axial center portions of the outer shell and the dead shaft.

[0009] The method of the present invention includes the steps of (1)positioning a rotatable contact roll on an axis of rotation parallel tothe axis of rotation of the bonding roll and closely adjacent anddownstream of the generator roll, (2) mounting the contact roll formovement radially with respect to the bonding roll into contact with thesingle face web on the bonding roll, and (3) loading the contact rollagainst the single face web with a force uniformly distributed acrossthe width of the web. Preferably, the loading step provides a force ofabout 5 pounds per lineal inch of web width.

[0010] The glue preferably comprises a starch adhesive and the methodincludes the step of heating the bonding roll. In accordance with thepreferred method, the contact roll is provided with a coating of arubber-like material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a front elevation view of the apparatus of the presentinvention.

[0012]FIG. 2 is an enlarged detail, partly in section, of the rollsupport mechanism on one end of the contact roll taken generally on line2-2 of FIG. 1.

[0013]FIG. 3 is an enlarged end elevation view taken on line 3-3 of FIG.2 of the roll support mechanism shown in the retracted inoperativeposition.

[0014]FIG. 4 is an end elevation similar to FIG. 3 showing the contactroll in the operative position and with glue applied to the web.

[0015]FIG. 5 is an enlarged sectional detail taken on line 8-8 of FIG.1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Referring to FIGS. 1 and 4, there is shown a portion of a singlefacer 10 similar in construction to the apparatus disclosed in aboveidentified U.S. Pat. No. 6,149,715. A medium web 11 is delivered to thesingle facer from an upstream source and is corrugated in the nip formedby a large diameter corrugating roll 12 (hereinafter sometimes referredto as the bonding roll) and a small diameter lower corrugating roll (notshown). Immediately downstream of the corrugating nip, a glue machineapplies a starch adhesive from a glue roll 14 to the flute tips of thecorrugated medium web 11 on the large diameter corrugating roll 12. Theadhesive is applied as glue lines 13 that form beads extendingcontinuously across the full width of the corrugated medium web 11 (seeFIG. 4). Immediately downstream from the glue roll 14, a delivery rollor generator roll 15 brings a liner web 16 from an upstream source intotangent contact with the glued flute tips of the medium web 11 on thelarge diameter roll 12 to form a freshly glued single face web 17. Inorder to form a good bond between the medium web 11 and the liner web16, the starch adhesive must be heated and dehydrated. The mechanism bywhich a starch base adhesive dries and cures includes initialgelatinization at a temperature of about 150° F. (65° C.), followed byentry into a green bond stage at further elevated temperature beginningat about 200° F. (93° C.).

[0017] As described in the above identified patent, the large diametercorrugating roll 12 is preferably internally heated, as with steam, to atemperature sufficient to heat the web and the starch adhesive to thegreen bond temperature. The large diameter bonding roll 12 provides acircumferential length downstream from the generator roll 15 on whichthe freshly glued single face web 17 may be held until adhesive greenbond strength has been attained. The primary force holding the liner web16 into contact with the glued flute tips of the medium web 11 isprovided by tension in the liner web 16 between the generator roll 15and a downstream takeoff roll (not shown) where the single face webleaves the bonding roll 12. It has been found, however, that in certaincases depending on paper type and caliper and flute size, the force bywhich the liner web 16 is pressed against the glued flute tips of thecorrugated medium web 11 could be increased slightly and the resultingbond enhanced. The beaded glue lines 13 should be spread uniformlyacross the full width of the web and this uniform spreading should takeplace before initial gelatinization of the starch. If the starch isallowed to gelatinize before spreading, not only is the adhesivedifficult to spread, but it will not penetrate into the paper webs aswell.

[0018] Thus, in accordance with the present invention, a soft surfacecontact roll 18 is positioned just downstream from the generator roll 15and mounted to be moved radially and with an adjustable force intocontact with the freshly glued single face web 17 on the bonding roll12. The soft contact roll 18 is positioned very close to and downstreamof the generator roll 15 so that it can assist in uniformly spreadingthe glue lines 13 before gelatinization of the starch occurs on theheated bonding roll 12. The progression of spreading of the glue lines13 is shown in FIG. 4 where the freshly placed beads on the flute tipsof the corrugated medium web 11 are progressively spread as contact ismade by the liner web 16. The contact roll 18 assures that the finalglue fillets 19 on opposite sides of the flute tips are formed rapidlyand before gelatinization. The contact roll 18 is supported with a rollsupport mechanism 20 that rotatably carries the roll by its oppositeends and is operative to vary the position of the roll radially withrespect to the bonding roll 12. The contact roll itself includes aunique construction that assures a more uniform load applied across thefull width of the single face web.

[0019] Referring also to FIGS. 2 and 3, the contact roll 18 includes acenter dead shaft 21 that has opposite stub shaft ends 22 which areconnected to the roll support mechanism 20. An outer roll shell 23 isrotatably supported on the dead shaft by two axially spaced bearings 24which are uniquely and strategically positioned, as will be described.The outer roll shell 23 includes a steel inner liner 25 covered by anouter cover of a soft rubber-like material. One particularly suitablematerial for the outer cover 26 is an EPDM material having a thicknessof about 0.2 inch (about 5 mm) having a 70 durometer.

[0020] The contact roll support mechanism 20 includes identicalmirror-image support sub-assemblies 27 attached to opposite ends of thedead shaft stub ends 22. Each support subassembly 27 is carried on amounting bracket 28 which, in turn, is attached to a cross frame member30. The ends of the cross frame member 30 are attached to oppositemachine side frame members 31. The side frame members 31 also carry theends of the generator roll 15 which, as shown in FIG. 1, is mounteddirectly below the contact roll 18 of the present invention.

[0021] Each roll support sub-assembly 27 has an eccentric coupling 32that includes an eccentric connector 45 fixed off-center to a stub shaftend 22 and further connected eccentrically to the end of a short pivotshaft 33. The pivot shaft is journaled for limited rotational movementin a bushing 39 mounted on a pivot shaft support 34. The pivot shafts 33are axially aligned and their axis is parallel to the axis of thecontact roll dead shaft 21. The pivot shaft supports are secured to themounting brackets 28 for the respective support sub-assemblies 27. Onthe opposite axial outer end of each pivot shaft 33, the rod end 29 of apneumatic cylinder 35 is eccentrically connected via a clevis 36. Thecylinder 35 is secured to the sub-assembly mounting bracket 28. In FIG.3, the cylinder 35 is shown with the cylinder rod 29 retracted and therubber covered surface of the contact roll 18 spaced from the singleface web 17 on the bonding roll 12 by a distance of about ½ inch (about12.5 mm). When the cylinders 35 of the two sub-assemblies 27 areextended simultaneously, the pivot shafts 33 are rotated through a smallacute angle and the eccentric coupling arrangement causes the dead shaft21 and the roll shell 23 journaled thereon to move generally radiallywith respect to the bonding roll 12 and into contact with the singleface web 17 which is carried on the bonding roll, as shown in FIG. 4.

[0022] The cylinders 35 are preferably operated to cause the contactroll 18 to rotatably bear against the single face web with a forcesufficient to provide a load of about 5 lbs. per lineal inch across thefull width of the web. This low load contact has been found to spreadthe glue lines 13 uniformly and rapidly and to significantly improve thebond between the liner and medium webs.

[0023] The contact roll 18 is specially constructed to resist deflectionand to assure that the load applied to the single face web is uniformacross the full width of the web. The axial center portion of the deadshaft 21 has a larger diameter than its end portion. Similarly, thecenter portion of the roll shell 23 is of a heavier construction thanthe respective opposite end portions. Specifically, the dead shaft 21includes a larger diameter tubular center portion 37 that joins reduceddiameter solid end shaft portions 38. The connection between the tubularcenter portion 37 and the opposite end shaft portions 38 comprises a hub44 on the axial inner end of each end shaft portion that is seated andfixed (as by welding) in a counterbore in the end of the tubular centerportion 37. The inner steel sleeve 25 of the roll shell 23 has an axialcenter portion 40 having a greater wall thickness than the opposite endportions 41 of the sleeve.

[0024] The roll shell 23 is journaled to rotate on the dead shaft 21with a pair of axially spaced bearings 24. The larger diameter centerportion 37 of the dead shaft 21 and the thicker center portion 40 of theroll sleeve 25 are preferably of approximately the same axial length.The bearings 24 are mounted with the inner bearing races on the reduceddiameter portions 38 of the dead shaft immediately adjacent the hubs 44.Similarly, the outer races of the bearings 42 abut a shoulder 43defining the transition between the thicker center portion 40 and theadjoining end portions 41 of the roll sleeve 25.

We claim:
 1. An apparatus for forming a single face corrugatedpaperboard web from a liner web and a corrugated medium web, the mediumweb being corrugated on a heated fluted bonding roll and having anadhesive applied to the flute tips while said medium web remains on saidbonding roll, the liner web being brought into initial tangent contactwith the glued flute tips of the corrugated medium on the bonding rollto form a composite single face web on said bonding roll, theimprovement comprising: a contact roll having an axis of rotationparallel to the rotational axis of the bonding roll and mounteddownstream of the line of initial tangent contact to press the singleface web against the bonding roll with a radial force distributeduniformly across the width of the single face web.
 2. The apparatus asset forth in claim 1 including a contact roll end support mechanismoperative to vary the position of the contact roll radially with respectto the bonding roll.
 3. The apparatus as set forth in claim 2 whereinthe contact roll comprises: a center dead shaft including stub shaftends connected to said end support mechanism; and, an outer shellrotatably supported on said dead shaft by a plurality of axially spacedbearings.
 4. The apparatus as set forth in claim 3 wherein said rollouter shell comprises a steel inner liner and a rubber outer cover. 5.The apparatus as set forth in claim 3 wherein said support mechanismcomprises: an eccentric coupling fixed to each stub shaft end, eachcoupling providing connection to a pivot shaft journaled for limitedrotation on a pivot axis parallel to the axis of the dead shaft; and, anactuator connected to each pivot shaft and operative to provide thelimited rotation thereto to vary the position of the contact roll. 6.The apparatus as set forth in claim 5 wherein each actuator comprises apneumatic cylinder having a cylinder rod end connected eccentrically toone of the pivot shafts.
 7. The apparatus as set forth in claim 3wherein the dead shaft includes a larger diameter axial center portionjoining reduced diameter opposite end portions; and, the outer shellhaving an axial center portion having a greater wall thickness joiningopposite shell end portions of reduced wall thickness.
 8. The apparatusas set forth in claim 7 wherein the axial center portion of said deadshaft and said outer shell are approximately equal in axial length. 9.The apparatus as set forth in claim 8 wherein the outer shell isrotatably supported by a pair of bearings positioned adjacent the endsof the axial center portion of the outer shell and the dead shaft. 10.In a single facer apparatus for forming a single face corrugatedpaperboard web from a liner web and a corrugated medium web, saidapparatus including a fluted bonding roll on which the medium web iscorrugated, a glue applicator that applies an adhesive to the flute tipsof the corrugated medium web while the medium web is on the bondingroll, and a generator roll that brings the liner web into initialtangent contact with the glued flute tips of the corrugated medium webon the bonding roll to form the single face web, a method for enhancingthe glue bond between the medium web and the liner web comprising thesteps of: (1) positioning a rotatable contact roll on a rotational axisparallel to the axis of rotation of the bonding roll closely adjacentand downstream of the generator roll; (2) mounting said contact roll formovement radially with respect to the bonding roll into contact with thesingle face web on the bonding roll; and, (3) loading said contact rollagainst the single face web with a force uniformly distributed acrossthe width of said web.
 11. The method as set forth in claim 10 whereinsaid loading provides a force of about 5 pounds per lineal inch of webwidth.
 12. The method as set forth in claim 10 wherein the adhesive is astarch adhesive and including the step of heating the bonding roll. 13.The method as set forth in claim 10 including the step of providing saidcontact roll with a coating of a rubber-like material.